1. Field of the Invention
The present invention relates to an electron-emitting device, an electron source comprising it, and an image-forming apparatus such as a display as its application. More particularly, the invention relates to a surface conduction electron-emitting device with a novel construction, an electron source using it, and an image-forming apparatus such as a display as its application.
2. Related Background Art
A surface conduction electron-emitting device utilizes a phenomenon that electrons are emitted by allowing an electric current to flow into an electroconductive film formed on a substrate.
As an example of the surface conduction electron-emitting device, the use of an SnO2 thin film for a device of this type [M. I. Elinson, xe2x80x9cRadio Eng. Electron Phys.xe2x80x9d, 10, 1290, (1965)], the use of an Au thin film [G. Ditmmer, xe2x80x9cThin Solid Filmsxe2x80x9d, 9, 317 (1972)], the use of an In2O3/SnO2 thin film [M. Hartwell and C. G. Fonsted, xe2x80x9cIEEE Trans. ED Conf.xe2x80x9d, 519 (1975)], the used of a carbon thin film [Hisashi Araki et al., xe2x80x9cShinku (Vacuum)xe2x80x9d, Vol. 26, No. 1, p. 22 (1983)], and the like have been reported.
In the above surface conduction electron-emitting device, prior to emitting electrons, the electroconductive film is generally subjected to an energization operation called xe2x80x9cformingxe2x80x9d, thereby obtaining a state where the electron emission is caused.
In this instance, xe2x80x9cformingxe2x80x9d is such an operation that a constant voltage or a voltage which gradually rises at a rate of, for example, about 1 V/min. is applied across the electroconductive film to allow a current to flow into the electroconductive film, and the electroconductive film is partially broken, deformed, or modified to enter an electrically high-resistant state, thereby obtaining a state where electrons are emitted.
Owing to the operation, a fissure is formed in a part of the electroconductive film. The phenomenon of the electron emission is attributed to the presence of the fissure. Although it is not completely clarified which portion the electron emission actually occurs in the fissure and a region around it are called xe2x80x9celectron emitting portionxe2x80x9d for convenience in some cases.
The present applicant has already expressed many proposals regarding the surface conduction electron-emitting device. For instance, the applicant has disclosed that it is preferable to perform the above xe2x80x9cformingxe2x80x9d by applying a pulse voltage to the electroconductive film in Japanese Patent No. 2854385 and U.S. Pat. Nos. 5,470,265 and 5,578,897.
In this instance, a waveform of the pulse voltage can be obtained by either one of a method of holding a peak value constant as shown in FIG. 5A and a method of gradually raising a peak value as shown in FIG. 5B. In consideration of the form and material of the device and forming conditions, it can be suitably selected.
It is found that subsequent to the forming, the pulse voltage is repetitively applied to the electron-emitting device in an atmosphere containing an organic material, so that both of a current (device current If) flowing into the device and a current (emission current Ie) accompanying with the electron emission increase. Such an operation is called xe2x80x9cactivationxe2x80x9d.
The operation forms a deposit containing carbon as a main component in the region including the fissure formed by the xe2x80x9cformingxe2x80x9d in the electroconductive film. The details of the operation are disclosed in Japanese Patent Application Laid-Open No. 7-235255.
When the above surface conduction electron-emitting device as mentioned above is applied to an image-forming apparatus, it is further required that the device has a low electric consumption and high luminance.
As properties of the electron-emitting device, therefore, it is required to further raise a ratio of the emission current Ie to the device current If, namely, an electron-emitting efficiency more than ever.
It is a matter of course that when such properties are improved, it is necessary that an aging change in properties by continuing the electron emission is not larger than that of the conventional technique.
It is an object of the present invention to provide an electron-emitting device excellent in electron-emitting characteristics, an electron source using it, and an image-forming apparatus using it.
According to the present invention, there is provided an electron-emitting device comprising a pair of electroconductors disposed on a substrate so as to be opposite to each other; and a pair of deposited films which are arranged so as to be connected to the pair of electroconductors, respectively, and which are disposed so as to sandwich a gap, and which contain carbon as a main component, wherein in the deposited film, phosphorus is contained within a range of 5 mol percent to 15 mol percent with respect to carbon.
According to the present invention, there is provided an electron-emitting device comprising a pair of device electrodes arranged so as to be opposite to each other on a substrate, an electroconductive film which is arranged so as to be connected to the pair of device electrodes and which has a fissure between the pair of device electrodes, and a deposit which is formed in the fissure and a region including the fissure, which has a gap with a width that is narrower than the fissure in the fissure, and which contains carbon as a main component, wherein in the deposit, phosphorus is contained within a range of 5 mol percent to 15 mol percent with respect to carbon.